1. Field of the Invention
The present invention relates to an ultrasonic transmitting unit which extends along a longitudinal axis and which is configured to transmit an ultrasonic vibration from a proximal direction toward a distal direction.
2. Description of the Related Art
Ultrasonic transmitting units extending along a longitudinal axis are disclosed in the specification of Jpn. PCT National Publication No. 2010-535089 and the specification of Jpn. PCT National Publication No. 2000-506431. Each of the ultrasonic transmitting units includes a columnar portion, and an ultrasonic probe connected to a distal direction side of the columnar portion. A vibration generating portion such as an ultrasonic vibrator which is configured to generate an ultrasonic vibration is attached to the columnar portion. The ultrasonic vibration generated in the vibration generating portion is transmitted from a proximal direction toward a distal direction through the columnar portion and the ultrasonic probe. That is, in the ultrasonic transmitting unit, the ultrasonic vibration is transmitted from the proximal direction toward the distal direction.
Furthermore, in the columnar portion of each ultrasonic transmitting unit, a sectional area changing portion (a horn portion) in which a sectional area perpendicular to the longitudinal axis changes is provided. By this sectional area changing portion, an amplitude of the ultrasonic vibration generated in the vibration generating portion is enlarged.